1. Field of the Invention
The present invention relates to an exhaust system for a vehicle such as an All-Terrain Vehicle (ATV), Side-by-Side Vehicle (SSV) or other off-road vehicle, for example. More particularly, the present invention relates to a catalyst installed in a muffler of an exhaust system for a vehicle such as an ATV, SSV or other off-road vehicle.
2. Description of the Related Art
ATVs, SSVs and other off-road vehicles are commonly used on a variety of harsh terrain including sand, dirt, and in shallow water. These vehicles are powered by internal combustion engines including exhaust systems that include a muffler and a catalyst for cleaning the exhaust gas before the exhaust gas is expelled into the environment.
In conventional exhaust systems including catalysts (e.g., catalytic converters), the catalyst causes resistance that blocks the flow of exhaust gas through the exhaust system. This resistance causes a substantial deterioration in performance of the vehicle.
To overcome this problem, the sizes of conventional catalysts have been increased to reduce the resistance caused thereby. However, this increase in size disadvantageously increases the size and cost of the catalyst, and the overall size and cost of the exhaust system.
A conventional exhaust system including a catalyst is disclosed in Japanese Unexamined Patent Application Publication No. 2001-115831. As seen in FIG. 1 of JP 2001-115831, the catalyst unit 3 is spaced from a pipe 1 and is supported by only a single support 6 in a cantilevered manner. Due to the single support 6, the catalyst unit 3 is susceptible to failure. Particularly, the shock caused by the off-road vehicle traversing rough and uneven terrain causes the catalyst unit 3 to separate from the single support 6, thus, causing failure.
In addition, since the catalyst unit 3 is spaced from the pipe 1 and is a separate unit from the pipe 1, the exhaust system of JP 2001-115831 is difficult to assemble, and it is difficult to accurately align the pipe 1 and the catalyst unit 3 such that the desired amount of exhaust gas passes from the pipe 1 through the catalyst unit 3. Thus, with the exhaust system of JP 2001-115831, it is difficult to assemble the muffler and catalyst unit, difficult to securely hold the catalyst unit in position, and difficult to control a precise amount of exhaust gas produced.
Another conventional exhaust system including a catalyst is disclosed in Japanese Unexamined Patent Application Publication No. 10-311214. As seen in FIGS. 2 and 6-9 of JP 10-311214, a catalyst 15 is provided in a forward portion of an expanded pipe 13 of an exhaust system and is spaced from the pipe 11. The catalyst 15 is supported by supports 16 and 17. In addition, a second catalytic converter 21 is provided in a rear portion of the expanded pipe 13 which is supported by supports 24 and 25 having openings.
Similar to JP 2001-115831, since the catalyst 15 of JP 10-311214 is spaced from the pipe 11 and is a separate unit, the exhaust system of JP 10-311214 is difficult to assemble, and it is difficult to accurately align the pipe 11 and the catalyst 15 such that the desired amount of exhaust gas passes through the catalyst 15. Thus, with the exhaust system of JP 10-311214, it is difficult to assemble the muffler and catalyst unit and difficult to control a precise amount of exhaust gas produced.